Laser beam machining apparatus

ABSTRACT

A laser beam machining apparatus includes a laser oscillator, a machining head which that machines a workpiece using the laser beam. An optical duct has an optical system to guide the laser beam form the laser oscillator to the machining head. Purge gas is supplied into the optical duct from a purge gas supply port, and the purge gas is output from a purge gas exhaust port. A detector detects presence of undesired gas in the optical duct.

TECHNICAL FIELD

The present invention relates to a laser beam machining apparatus whichcarries out welding and cutting and is capable of detecting mixing ofimpure gas in purge gas filling a light guide duct guiding a laser beam.

BACKGROUND ART

Various types of laser machining apparatuses are known. For example,Japanese Patent Application Laid-Open Publication No. 5-8079 (see page2, FIGS. 1 and 2) discloses a conventional laser beam machiningapparatus that transmits a laser beam stably for long time and can weldand cut a subject to be machined with high accuracy. This laser beammachining apparatus includes a laser oscillator, a laser robot, anoptical duct, and a machining gas supply unit. The laser oscillator hasa beam transmission line including a laser outgoing port of an airtightmechanism. The laser robot has an articulated configuration which canemit a laser beam to an arbitrary position of the subject to bemachined. The optical duct guides the laser beam so that an optical axisof the laser beam between the laser oscillator and the laser robot doesnot shift. The machining gas supply unit detects pressure in the opticalduct and supplies a predetermined machining gas into the optical duct sothat the pressure in the optical duct becomes higher than externalpressure. Such a configuration prevents fume and dust generated at thetime of the laser beam machining from entering the optical duct througha tip of the laser robot.

Japanese Patent Application Laid-Open Publication No. 6-17120 (see pages2 to 3, FIG. 1) discloses a laser annealing apparatus capable ofcontrolling intensity of a laser beam accurately according to acondition where a subject to be machined undergoes a laser annealingprocess. The laser annealing apparatus has such a configuration that thelaser oscillator and a chamber in which the subject to be machined andto undergo the laser annealing process is arranged are connected by theoptical duct. The laser annealing apparatus adjusts the intensity of thelaser beam emitted to the subject to be machined in the chamber based onpurge gas which does not absorb the laser beam transmitting through theoptical duct, and concentration of control gas having predeterminedabsorbance with respect to the laser beam. The optical duct, therefore,has a detecting sensor which detects the concentration of the controlgas in the optical duct, and a quantity of the control gas to besupplied into the optical duct is controlled based on a signal obtainedin such a manner that the detecting sensor detects the concentration ofthe control gas.

In the conventional laser beam machining apparatus disclosed in JapanesePatent Application Laid-Open Publication No. 5-8079, however, air mightenter the optical duct. One of causes that the air enters the opticalduct is a configuration of the optical duct. As shown in FIG. 1 of thispublication, for example, the optical duct which connects the laseroscillator and the laser robot does not have a linear form, and theoptical path is bent at a plurality of portions. Such an optical duct isnormally constituted so that bellows or the like connects a plurality ofpipes. The laser beam machining apparatus of the first prior art has thelaser robot in which a position to which the laser beam is emitted canbe moved so that the laser beam can be emitted to an arbitrary positionof a subject to be machined. In the laser beam machining apparatushaving such a configuration, for example, a bellows section composing apart of the optical duct occasionally moves according to a changingoperation of the emitting position of the laser robot which is performedin order to change the laser beam emitting position, or when the laserbeam machining is stopped, pressure in the optical duct temporarilydrops. As a result, for example, outside air enters the optical ductthrough joints of the pipes composing the optical duct or joints betweenthe pipes and the bellows.

Another cause that the air might enter the optical duct is machining gasto be supplied into the optical duct, and this is caused by using airsucked from a compressor into the optical duct as the machining gas.

If the air enters the optical duct, when thinner, paint, or the like isused in a vicinity of the optical duct, impure gas such as laser beamabsorbing gas (thinner, trichloroethylene, acrylic combustion gas,fluorocarbon gas, SF₆, organic compound, and the like) enters theoptical duct. The impure gas causes power distribution of the laser beamand increase in attenuation of the laser beam, and as a result,characteristics of the laser beam are deteriorated, and thus machiningability of the laser beam machining apparatus is deteriorated.

When anomalous output of the laser beam occurs, a defect in the laseroscillator is firstly regarded as a cause of the fault. After variousfactors which cause the fault in the output of the laser beam areeliminated, it is frequently found that the intrusion of the impure gasinto the optical duct is the cause of the anomalous output of the laserbeam. That is to say, the impure gas in the optical duct cannot bespecified as the cause of the anomalous output of the laser beam in theearly stage of the checkup of the causes. During the checkup of thecauses, therefore, the machining cannot be carried out by the laser beammachining apparatus, and thus the impure gas is also a cause fordeteriorating working efficiency.

In the laser annealing apparatus disclosed in Japanese PatentApplication Laid-Open Publication No. 6-17120, the detecting sensorwhich detects the control gas is provided in the optical duct, but thedetecting sensor detects the concentration of the control gas whichcontrols the output of the laser beam and does not detect the impuregas. That is to say, even if the impure gas such as the laser absorbinggas enters the optical duct, the detecting sensor cannot detect theintrusion of the impure gas.

The present invention has been achieved in order to solve the aboveproblems, and its object is to obtain the laser beam machining apparatuswhich is capable of detecting impure gas intruded into the optical duct.

DISCLOSURE OF THE INVENTION

A laser beam machining apparatus according to the present inventionincludes a laser oscillator which oscillates a laser beam, the laseroscillator having a laser beam outgoing port to output the laser beam; amachining head which machines a workpiece with the laser beam; anoptical duct with an optical system to guide the laser beam from thelaser beam outgoing port to the machining head; a purge gas supply portthat opens into the optical duct and situated near any one of the laserbeam outgoing port and the machining head, wherein a purge gas supplyunit supplies purge gas into the optical duct from the purge gas supplyport; a purge gas exhaust port that opens into the optical duct andsituated near any one of the laser beam outgoing port and the machininghead, wherein the purge gas in the optical duct is output from the purgegas exhaust port; and an odor sensor that detects undesired gas in aportion of the optical duct from the laser beam outgoing port to themachining head, wherein the undesired gas is a gas that makes the laserbeam anomalous.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a laser beam machining apparatusaccording to a first embodiment of the present invention;

FIG. 2 illustrates how a gas detector is attached to an optical duct;

FIG. 3 is a flowchart of a process to detect anomaly in the laser beammachining apparatus according to the first embodiment;

FIG. 4 is a flowchart of a process of calibration executed using the gasdetector;

FIG. 5 is a schematic diagram of a laser beam machining apparatusaccording to a second embodiment of the present invention;

FIG. 6 is a flowchart of a process to detect an anomaly in the laserbeam machining apparatus;

FIG. 7 is a schematic diagram of a laser beam machining apparatusaccording to a third embodiment of the present invention;

FIG. 8 is to explain how the odor sensor detects anomalous portions;

FIG. 9 is a flowchart of a process to detect an anomaly in the laserbeam machining apparatus according to the third embodiment;

FIG. 10 is a schematic diagram of a laser beam machining apparatusaccording to a fourth embodiment of the present invention;

FIG. 11 is a flowchart of a process to detect an anomaly in the laserbeam machining apparatus according to the fourth embodiment;

FIG. 12 is a schematic diagram of a laser beam machining apparatusaccording to a fifth embodiment of the present invention;

FIG. 13 is to explain how the odor sensor detects anomalous portions inthe laser beam machining apparatus according to the fifth embodiment;

FIG. 14 is a flowchart of a process to detect an anomaly in the laserbeam machining apparatus according to the fifth embodiment;

FIG. 15 illustrates an example in which the gas detector is attached tothe optical duct;

FIG. 16 is a flowchart of a process of calibration executed using thegas detector;

FIG. 17 illustrates an example in which the gas detector is mounted tothe optical duct; and

FIG. 18 is a flowchart of a process of calibration executed using thegas detector.

BEST MODE FOR CARRYING OUT THE INVENTION

Exemplary embodiments of laser beam machining apparatus according to thepresent invention are explained in detail with reference to theaccompanying drawings.

FIRST EMBODIMENT

A first embodiment of the present invention is explained with referenceto FIGS. 1 to 4. FIG. 1 is a schematic diagram of the laser beammachining apparatus according to the first embodiment of the presentinvention. FIG. 2 illustrates how a gas detector is attached to anoptical duct. FIG. 3 is a flowchart of a process to detect anomaly inthe laser beam machining apparatus according to the first embodiment.FIG. 4 is a flowchart of a process of calibration executed using the gasdetector.

The laser beam machining apparatus includes a laser oscillator 11, suchas a carbon dioxide gas laser oscillator (oscillation wavelength: 10.6micro millimeters) which oscillates a laser beam, a machining head 21which emits a laser beam output from the laser oscillator 11 to aworkpiece (subject to be machined) 100 to be machined, and an opticalduct 30 which guides the laser beam emerged from the laser oscillator 11to the machining head 21 while an optical axis of the laser beam ismaintained. In the drawings, an alternate long and short dash line Lshows the laser beam.

The optical duct 30 is shaped as English letter L. In other words, twopipes 31 a and 31 b are joined at right angle via a stretchable bellows33. An optical system such as a bend mirror 34 is provided into theoptical duct 30 so as to guide the laser beam L from a laser beamoutgoing port 12 of the laser oscillator 11 to the machining head 21 andcondensing the laser beam L onto a tip (hereinafter, a machining headtip) 22 of the machining head 21. For example, the bend mirror 34 bendsa path of the laser beam L emitted from the laser beam outgoing port 12of the laser oscillator 11 towards the machining head 21 by 90 degreesin the configuration of FIG. 1. The pipe 31 b connected with themachining head 21 can move to a direction of an arrow A in the drawingalong a frame 23 by a guiding configuration or a driving mechanism, notshown, so that a relative moving operation is performed between thelaser beam L and the workpiece 100. According to the movement of thepipe 31 b connected with the machining head 21 along the frame 23, thebellows 33 expands and contracts.

A purge gas supply port 35 which is used for supplying purge gas whichdoes not affect absorbance of the laser beam L passing through theoptical duct 30 is provided in a vicinity of the laser beam outgoingport 12 of the laser oscillator 11 on the optical duct 30. A purge gasexhaust port 36 to exhaust the purge gas out of the optical duct 30 isprovided near the machining head 21 on the optical duct 30. The purgegas supply port 35 is connected with a nitrogen supply section 41 and acompressor 42 via a valve 44 which is switched exclusively. The nitrogensupply section 41 supplies nitrogen as the purge gas. The compressor 42supplies sucked and compressed air as the purge gas. An inlet port whichsucks air of the compressor 42 has a filter 43. The filter 43 iscomposed of activated carbon or the like having a function foreliminating moisture, dust, organic compound, and the like in a roomwhere the laser beam machining apparatus is installed so as to preventthem from intruding into the optical duct 30. The pressure in theoptical duct 30 is set to be predetermined pressure (for example, whenair (purge air) is used as the purge gas, a flow rate is 100 L/min., anda pressure difference is not less than 0.06 kPa) by the purge gas supplyport 35 and the purge gas exhaust port 36 provided on the optical duct30. The laser beam machining apparatus further includes at least one gasdetector 50, a control notification section 61, and an anomaly displaysection 62. The gas detector 50 detects intrusion of impure gas in theoptical duct 30 and outputs an anomaly detection signal. The controlnotification section 61 controls the laser beam machining apparatus andwhen receiving the anomaly detection signal from the gas detector 50,notifies anomaly to a operator of the laser beam machining apparatus.The anomaly display section 62 makes the operator recognize the anomalyby means of the notification from the control notification section 61.The control notification section 61 controls the laser oscillator 11based on the anomaly detection signal output from the gas detector 50and a filter replacement signal which is output from the compressor 42when the filter 43 is replaced, and controls the entire laser beammachining apparatus based on an instruction from the operator. Thecontrol positing section 61 controls calibration of the gas detector 50when the laser beam machining apparatus is booted. The anomaly displaysection 62 is composed of, for example, a CRT (Cathode Ray Tube), aliquid crystal display, an indicator which notifying various anomalies,or a buzzer which is provided in the laser beam machining apparatus. Thecontrol notification section 61 notifies the anomaly due to theintrusion of the impure gas to the operator.

The gas detector 50 includes, as shown in FIG. 2, an odor sensor 51which detects the impure gas in the optical duct 30, and a sensorcalibrator 52 which calibrates the odor sensor 51 when the laser beammachining apparatus is booted. The gas detector 50 is provided on aconcave portion 70 which is formed in such a manner that a portion of aside wall of the optical duct 30 is dented from the inside to theoutside of the optical duct 30. The concave portion 70 has a surfaceparallel with an optical axis in the optical duct 30. The concaveportion 70 is formed so as to be surrounded by a peripheral surface 71connected with the optical duct 30, a first side surface 72 which ispositioned on a lower stream side of the concave portion 70 and connectsan outer peripheral surface of the optical duct 30 with the peripheralsurface 71 of the concave portion 70, and a second side surface 73 whichis positioned on an upper stream side of the concave portion 70 andconnects the outer peripheral surface of the optical duct 30 with theperipheral surface 71 of the concave portion 70. The first side surface72 has an angle which is approximately vertical to an extended directionof the optical duct 30, but the second side surface 73 has an angle oftilt which is not vertical but gentle from an inner wall of the opticalduct 30 towards the peripheral surface 71 of the concave portion 70which is the farthest from a center of the optical duct 30.

The odor sensor 51 is provided on the first side surface 72 of theconcave portion 70 so as to oppose to a flow of the purge gas G flowingin the optical duct 30. As the odor sensor 51, a hot wire semiconductorsensor which can detect atmosphere components such as combustible gas,toxic gas, and odor component can be used. The hot wire semiconductorsensor has a two terminal configuration that includes a gas sensitivesection and a lead wire section. The gas sensitive section isconstituted so that a metallic oxide semiconductor such as tin oxide isarranged around a coil which is formed by a linear resister made ofnoble metal wire such as a platinum or platinum alloy wire. The leadwire section is constituted so that both ends of the linear resister areextended to the outside of the gas sensitive section. The gas detectoris electrically connected with the linear resister of the hot wiresemiconductor sensor having such a configuration so as to have apredetermined temperature, and detects a change in resistance of the gassensitive section due to gas absorption so as to detect the gascomponent. As the odor sensor, for example, a hot wire semiconductorsensor CH-E (model name) made by New Cosmos Electric Co., Ltd. can beused.

The sensor calibrator 52 includes a calibration gas supply section 53, anozzle 54, and an electromagnetic valve 55. The calibration gas supplysection 53 supplies gas for calibration of the odor sensor 51(hereinafter, “calibration gas”). The nozzle 54 is arranged on thesecond side surface 73 of the concave portion 70 opposed to the odorsensor 51 (so that the calibration gas is blown to the same direction asthe flow of the purge gas G). The electromagnetic valve 55 controls soas to supply the calibration gas into the optical duct 30 at the time ofthe calibration and not to supply the calibration gas into the opticalduct 30 at time other than the calibration. Opening and closing statesof the electromagnetic valve 55 are controlled by the controlnotification section 61.

The sensor calibrator 52 obtains a standard of the operation of the odorsensor 51 in the environment without the impure gas in order to detect achange in the odor sensor 51 when the impure gas intruded. For thisreason, it is desirable that the calibration gas supply section 53supplies gas with the same composition as that of the purge gas Gsupplied at the time of the laser beam machining. Even if, however, thegas does not have the same composition as that of the purge gas G, thecalibration gas supply section 53 may supply nitrogen gas or oxygen gas,which is not detected by the odor sensor 51, as the calibration gas.That the calibration gas is allowed to flow in the odor sensor 51 inorder to obtain an initial value for determination which state is notanomalous is called as calibration.

The gas detector 50 is provided near the purge gas exhaust port 36 ofthe optical duct 30 in the laser beam machining apparatus so as todetect the intrusion of the impure gas into the optical duct 30 whichcauses the anomalies such as the power distribution of the laser beam Land the increase in attenuation of the laser beam L. The impure gas canbe detected, therefore, made at an initial state whether the anomaliesof the laser beam L are caused by the impure gas or another reason.

The process to detect an anomaly in the laser beam machining apparatuswill be explained using FIG. 3. To boot the laser beam machiningapparatus, the compressor 42 is booted (step S1) whereby the opticalduct 30 is filled with gas (air).

Next, calibration of the odor sensor 51 is executed (step S2) as shownin FIG. 4. The electromagnetic valve 55 which is provided between thecalibration gas supply port 53 and the nozzle 54 is opened (step S201),and calibration gas is blown from the nozzle 54 onto the odor sensor 51so that the calibration is started (step S202). The calibration gas isblown onto the odor sensor 51 for predetermined time (normally, a fewminutes), and when the calibration is ended (step S203), the odor sensor51 outputs a signal showing completion of the calibration to the controlnotification section 61 (step S204). The control notification section 61closes the electromagnetic valve 55 (step S205), so that the calibrationprocess is ended.

Referring again to FIG. 3, upon completion of the calibration of theodor sensor 51, the workpiece 100 is located on a predetermined positionand the workpiece 100 is machined (step S3). During the machining, theodor sensor 51 continues to detect an anomaly, that is, intrusion of theimpure gas in the optical duct 30 (step S4). When there is no anomaly(No at step S4), the machining is continued (step S12).

On the other hand, when there is an anomaly (Yes at step S4), the odorsensor 51 outputs an anomaly detection signal to the controlnotification section 61. The control notification section 61 decides asto how many times the anomaly detection signal is received after thelaser beam machining apparatus is booted (step S5). When an anomalydetection signal is received for the first time (“first” in FIG. 3), thecontrol notification section 61 sends information to the anomaly displaysection 62 to display a notice to inspect the compressor 42 and itsvicinity (step S6). This notice is displayed on the anomaly displaysection 62.

When such a notice is displayed, the operator inspects the compressor 42and its vicinity for anomaly (step S8). Particularly, the operatorinspects the atmosphere around the compressor 42, and when anomaly isnot found, the filter 43 of the compressor 42 is replaced. When thefilter 43 of the compressor 42 is replaced, in a state where thecompressor 42 is connected with the optical duct 30, the valve 44 isswitched so that the nitrogen supply section 41 is connected with theoptical duct 30, so that the nitrogen is supplied to the optical duct30. The filter 43 provided at the inlet port of the compressor 42 isreplaced, and after the replacement of the filter 43, the compressor 42outputs a replacement completion signal showing that the replacement iscompleted to the control notification section 61. In the state where thenitrogen supply section 41 is connected with the optical duct 30, thevalve 44 is switched so that the compressor 42 is connected with theoptical duct 30, so that the air is again supplied into the optical duct30. The valve 44 may be switched by the control notification section 61or by the operator. At the time of switching by the control notificationsection 61, when the control notification section 61 receives theanomaly detection signal from the odor sensor 51, the valve 44 isswitched from the compressor 42 to the nitrogen supply section 41. Whenthe control notification section 61 receives the replacement completionsignal from the compressor 42, the valve 44 may be switched from thenitrogen supply section 41 to the compressor 42. During the inspection,the laser beam machining process can be continued by using nitrogen gasas the purge gas.

Upon completion of the inspection, the system control returns to stepS4, and the odor sensor 51 again detects whether there is an anomaly.When there is an anomaly (Yes at step S4), the odor sensor 51 outputsthe anomaly detection signal to the control notification section 61. Thecontrol notification section 61 decides as to how many times the anomalydetection signal is received after the laser beam machining apparatus isbooted (step S5). When an anomaly detection signal is received for thesecond time (“second” in FIG. 3), the control notification section 61sends information to the anomaly display section 62 to display a noticeto inspect transmission line parts (step S7). This information isdisplayed on the anomaly display section 62.

When such a notice is displayed, the operator inspects the transmissionline parts such as the pipes 31 a and 31 b and the bellows 33 of theoptical duct 30 to be the transmission line of the laser beam L forburning and deterioration. If the operator finds faulty parts, hereplaces the faulty parts (step S8).

Upon completion of the inspection, the system control returns to stepS4, and the odor sensor 51 again detects whether there is an anomaly(step S4). When there is an anomaly (Yes at step S4), the odor sensor 51outputs the anomaly detection signal to the control notification section61. The control notification section 61 decides how many times theanomaly detection signal is received after the laser beam machiningapparatus is booted (step S5). When an anomaly detection signal isreceived for the third time or more (“third and after” in FIG. 3), thecontrol notification section 61 sends information to the anomaly displaysection 62 to display a notice to inspect the entire laser beammachining apparatus (step S7). This information is displayed on theanomaly display section 62.

Upon receiving of the information, the operator judges whether themachining can be carried out without affecting machining quality if theoutput of the laser oscillator 11 is lowered. The laser oscillator 11 iscontrolled based on the result of the judgment (step S10). When it ispossible to carry out the machining without affecting the machiningquality by lowering the output of the laser beam L, for example, thecontrol notification section 61 adjusts the output of the laseroscillator 11 to a level where the machining quality is not affected,and the machining is continued. The process ends after the machining iscompleted. Meanwhile, if it is difficult to carry out the machining evenafter lowering the output of the laser beam L, the control notificationsection 61 stops the laser oscillator 11. The operator inspects theparts in the laser beam machining apparatus such as a machine includingthe frame 23 and the laser oscillator 11 except for the inspected andreplaced compressor 42 and the optical duct 30. When anomaly is found,the operator replaces an anomalous part, and the process is ended.

According to the first embodiment, the odor sensor 51 is provided nearthe purge gas exhaust port 36 so as to be capable of detecting theintrusion of the impure gas in the entire purge gas G in the opticalduct 30. The intrusion of the impure gas can be specified as a cause ofthe anomalous laser beam L, as a result. The odor sensor 51 outputs theanomaly detection signal to the control notification section 61 so thata cause of the anomaly can be checked upon effectively. A replacementtiming of the filter 43 provided to the inlet port of the compressor 42can be judged based on the cause. The laser oscillator 11 can becontrolled based on the anomaly detection signal from the controlnotification section 61.

The odor sensor 51 is mounted to the first side surface 72 on theconcave portion 70 of the optical duct 30 so as to be opposed to theflow of the purge gas G, and the nozzle 54 is mounted to the second sidesurface 73 on the concave portion 70 just in front of the odor sensor 51so that a flowing direction of the calibration gas is the same as thatof the purge gas G. The calibration of the odor sensor 51 can be,therefore, executed efficiently. Since the second side surface 73 isformed so as to tilt from the upper stream side of the optical duct 30to the peripheral surface 71 of the concave portion 70, the purge gas Geasily flows into the concave portion 70, so that the odor sensor 51 candetect the impure gas effectively.

SECOND EMBODIMENT

FIG. 5 is a schematic diagram of a laser beam machining apparatusaccording to a second embodiment of the present invention. FIG. 6 is aflowchart of a process to detect an anomaly in the laser beam machiningapparatus. Components which have same or similar configuration or sameor similar functions as those in FIG. 1 are designated by the samereference numbers, and the explanation thereof is omitted.

As shown in FIG. 5, in the laser beam machining apparatus of the secondembodiment, the gas detector 50 is positioned near the purge gas supplyport 35. Although not shown, the gas detector may be provided inplurality. The other parts of configuration are the same as those inFIG. 1. It is preferable that the gas detector 50 is positioned oppositeto the purge gas supply port 35 or slightly down stream side. The gasdetector 50 is provided on the concave portion 70 on the optical duct 30as shown in FIG. 2 of the first embodiment. The gas detector 50 isprovided near the purge gas supply port 35, so as to be capable ofimmediately detecting the impure gas which intrudes from the compressor42, for example.

The process of detecting an anomaly in the laser beam machiningapparatus according to the second embodiment is explained using FIG. 6.The steps S1 to S4 and S11 are same as those explained with reference toFIG. 3 and correspond to steps S21 to S24 and S30 respectively in FIG.6. That is to say, after the compressor 42 is booted (step S21) wherebythe optical duct 30 is filled with gas (air), the calibration of theodor sensor 51 is executed (step S22) in same manner as explained withreference to FIG. 4.

The machining of the workpiece is started (step S23) and the gasdetector 50 detects whether there is an anomaly. When there is noanomaly, the machining is continued (step S30), and completed.

When an anomaly is detected (Yes at step S24), the odor sensor 51outputs the anomaly detection signal to the control notification section61. The control notification section 61 determines as to how many timesthe anomaly detection signal is notified after the laser beam machiningapparatus is booted (step S25). When the anomaly detection signal is afirst one (“first” at step S25), the control notification section 61notifies information that shows an inspection of the compressor 42 andits vicinity (step S26) so that this information is displayed on theanomaly display section 62. The operator makes the inspection accordingto the information (step S27). Since the inspection of the compressor 42and its vicinity by the operator is similar to that in the firstembodiment, the explanation thereof is omitted.

After the inspection and the replacement are completed by the operator,the sequence returns to step S24, and the odor sensor 51 detects anomalydue to the impure gas in the purge gas. When the odor sensor 51 detectsthe anomaly due to the impure gas in the purge gas (Yes at step S24),the odor sensor 51 outputs the anomaly detection signal to the controlnotification section 61. The control notification section 61 determinesas to how many times the anomaly detection signal is notified after thelaser beam machining apparatus is booted (step S25). Since the anomalydetection signal is a second one here (“second” at step S25), thecontrol notification section 61 notifies information shows that aninspection of parts of the laser beam machining apparatus other than thecompressor 42 and its vicinity is necessary to the anomaly displaysection 62 (step S28) so that this information is displayed on theanomaly display section 62.

When the information is received, the operator judges whether themachining can be executed without affecting the machining quality in thestate where the output of the laser oscillator 11 is lowered, and thestate of the laser oscillator 11 is controlled based on the judgedresult (step S29). When the laser machining is possible like the firstembodiment, the control notification section 61 adjusts the output ofthe laser oscillator 11 to a level where the machining quality is notaffected and the machining is continued. When the continuation of themachining is difficult, the laser oscillator 11 is stopped. After thelaser oscillator 11 is stopped, the operator inspects parts in the lasermachining apparatus, such as the transmission line parts including thepipes 31 a and 31 b and the bellows 33 of the optical duct 30 to be thetransmission line of the laser beam L except for the inspected andreplaced compressor 42, and the machine such as the frame 23 and thelaser oscillator 11. When anomaly is detected, an anomalous part isreplaced, and the process is ended.

According to the second embodiment, the odor sensor 51 is positionednear the purge gas supply port 35 of the optical duct 30, and theanomaly detection signal detected by the odor sensor 51 is output to thecontrol notification section 61. The odor sensor 51 can, therefore,detect intrusion of the impure gas due to atmospheric gas in thecompressor 42 or its vicinity, and its cause can be checked uponeffectively. The replacement timing of the filter 43 to be mounted tothe inlet port of the compressor 42 can be determined by the informationnotified from the control notification section 61, and the valve 44 canbe switched from the compressor 42 to the nitrogen supply section 41.The laser oscillator 11 can be controlled based on the anomaly detectionsignal from the control notification section 61.

THIRD EMBODIMENT

FIG. 7 is a schematic diagram of a laser beam machining apparatusaccording to a third embodiment of the present invention. FIG. 8 is toexplain how the odor sensor detects anomalous portions. FIG. 9 is aflowchart of a process to detect an anomaly in the laser beam machiningapparatus according to the third embodiment. Components which have sameor similar configuration or same or similar functions as those in FIG. 1are designated by the same reference numbers, and the explanationthereof is omitted.

As shown in FIG. 7, in the laser beam machining apparatus of the thirdembodiment, a first gas detector 50 a is provided near the purge gasexhaust port 36, and a second gas detector 50 b is provided near thepurge gas supply port 35. Although not shown, the first and second gasdetectors may be provided in plurality. The other parts of theconfiguration are the same as those in FIG. 1. A position where thesecond gas detector 50 b is provided is desirably a portion in theoptical duct 30 opposed to the purge gas supply port 35 or its slightlylower stream side. The gas detectors 50 a and 50 b are, as shown in FIG.2 of the first embodiment, arranged on the concave portion 70 of theoptical duct 30.

FIG. 8 is a diagram of causes which are conceivable from anomalydetection conditions of the first gas detector and the second gasdetector. In the drawing, a circle means that an anomaly is notdetected, and a cross means that an anomaly is detected. When both thefirst and the second gas detectors 50 a and 50 b are normal, it meansthat no impure gas flows into the optical duct 30, and thus themachining process can be continued. When the first gas detector 50 adetects an anomaly and the second gas detector 50 b is normal, adetermination can be made that its first cause is impure gas which isintruded from the transmission line parts. When both the first and thesecond gas detectors 50 a and 50 b detect anomaly, a determination canbe made that its first cause is anomaly of atmosphere around thecompressor 42 or anomaly of the filter 43 of the compressor 42. Adetermination can be made that its second cause is the impure gas whichis intruded from the transmission line parts.

The first gas detector 50 a is provided near the purge gas exhaust port36 on the optical duct 30, and the second gas detector 50 b is providednear the purge gas supply port 35 on the optical duct 30. Thedetermination can be made whether the cause of the intrusion of theimpure gas is the atmosphere around the compressor 42, the filter 43 ofthe compressor 42, or the transmission line parts.

The process of detecting anomaly in the laser beam machining apparatusis explained below with reference to the flowchart of FIG. 9. The sameprocess as steps S1 to S3 explained in FIG. 3 of the first embodiment isexecuted, so that the machining by the laser beam machining apparatus isstarted (steps S41 to S43). That is to say, after the compressor 42 isbooted and the optical duct 30 is filled with gas (air), the calibrationof the odor sensor 51 is executed, and the machining is started. Thecalibration of the odor sensor 51 is executed in the procedure explainedin FIG. 4 of the first embodiment.

During the laser beam machining, the odor sensors 51 of the first andthe second gas detectors 50 a and 50 b continue to detect intrusion ofthe impure gas in the optical duct 30 (step S44). When the two gasdetectors 50 a and 50 b do not detect anomaly (“normal” at step S44),the machining is continued (step S53). The process ends when themachining process is completed.

When the first and the second gas detectors 50 a and 50 b detect anomalydue to the impure gas intruded in the purge gas in the optical duct 30(“the first and the second gas detectors are anomalous” at step S44),the first and the second gas detectors 50 a and 50 b output anomalydetection signals to the control notification section 61. The controlnotification section 61 notifies information showing that the compressor42 and its vicinity are inspected to the anomaly display section 62(step S45), so that this information is displayed on the anomaly displaysection 62. The operator makes an inspection according to theinformation and replaces the parts if necessary (step S46). Since theinspection and the replacement of the compressor 42 and its vicinity bythe operator are the same as those in the first embodiment, theexplanation thereof is omitted.

When the two gas detectors 50 a and 50 b do not detect anomaly due tothe impure gas in the purge gas (“normal” at step S47), the machiningprocess is continued (step S53). The process ends after the machiningprocess is completed.

Meanwhile, when the first gas detector 50 a detects anomaly due to theimpure gas in the purge gas (“only the first gas detector is anomalous”at step S47), or when only the first gas detector detects anomaly atstep S44 (“only the first gas detector is anomalous” at step S44), thefirst gas detector 50 a outputs the anomaly detection signal to thecontrol notification section 61. The control notification section 61notifies information showing that the transmission line parts areinspected to the anomaly display section 62 (step S48), so that thisinformation is displayed on the anomaly display section 62. The operatormakes an inspection based on the information, and replaces the parts ifnecessary (step S49). Specifically, the operator inspects thetransmission line parts such as the pipes 31 a and 31 b and the bellows33 of the optical duct 30 to be the transmission line of the laser beamL for burning or deterioration. When anomaly is found, the operatorreplaces an anomalous part.

After the inspection and the replacement by the operator are completed,the two gas detectors 50 a and 50 b detect impure gas in the opticalduct 30 (step S50). When the gas detectors 50 a and 50 b do not detectanomaly due to impure gas in the purge gas (No at step S50), themachining process is continued (step S53). The process ends after themachining process is completed. At least one of the gas detectors 50 aand 50 b detects the anomaly due to the impure gas in the purge gas (Yesat step S50), the gas detector 50 a or 50 b which detects the anomalyoutputs the anomaly detection signal to the control notification section61. The control notification section 61 notifies information showingthat the inspection of the entire laser beam machining apparatus isnecessary to the anomaly display section 62 (step S51), and thisinformation is displayed on the anomaly display section 62.

When this information is received, the operator judges whether themachining can be executed without affecting the machining quality in thestate where the output of the laser oscillator 11 is lowered, andcontrols the state of the laser oscillator 11 based on the judged result(step S52). When the laser beam machining is possible like the firstembodiment, the control notification section 61 adjusts the output ofthe laser oscillator 11 to a level where the machining quality is notaffected so that the machining is continued. When the continuation ofthe machining is difficult, the laser oscillator 11 is stopped. Afterthe laser oscillator 11 is stopped, the operator inspects the parts inthe laser beam machining apparatus, such as the machine including theframe 23 and the laser oscillator 11 except for the inspected andreplaced compressor 42 and the optical duct 30. When anomaly is found,an anomalous part is replaced, and the process is ended.

According to the third embodiment, the odor sensor 51 is provided nearthe purge gas exhaust port 36 and the purge gas supply port 35, so as tobe capable of detecting intrusion of the impure gas in the purge gas. Adetermination can be made whether its cause is the compressor 42 or thetransmission line parts. As a result, a location as the cause of theanomalous laser beam L can be checked upon effectively. The anomaly dueto the intrusion of the impure gas is output to the control notificationsection 61, so that the replacement timing of the filter 43 attached tothe inlet port of the compressor 42 can be determined, and anomaliessuch as burning and deterioration of the transmission line parts can beeasily found. The laser oscillator 11 can be controlled based on theanomaly detection signal from the control notification section 61.

FOURTH EMBODIMENT

FIG. 10 is a schematic diagram of a laser beam machining apparatusaccording to a fourth embodiment of the present invention. FIG. 11 is aflowchart of a process to detect an anomaly in the laser beam machiningapparatus according to the fourth embodiment. Components which have sameor similar configuration or same or similar functions as those in FIG. 1are designated by the same reference numbers, and the explanationthereof is omitted.

As shown in FIG. 10, in the laser beam machining apparatus of the fourthembodiment, a gas detector 50 is provided near the inlet port of thecompressor 42. Although not shown, the gas detector may be provided inplurality. The other parts of the configuration are the same as those inFIG. 1. The gas detector 50 is provided near the inlet port of thecompressor 42, so as to detect the impure gas intruded from thecompressor 42 immediately.

The process of detecting the anomaly in the laser beam machiningapparatus is explained below with reference to the flowchart in FIG. 11.The calibration of the odor sensor 51 is executed for predetermined time(step S61), and after the compressor 42 is booted and the optical duct30 is filled with gas (air) (step S62), the machining is started (stepS63). The calibration of the odor sensor 51 is executed in the procedureexplained in FIG. 4 of the first embodiment.

The gas detector 50 detects anomaly of the atmosphere around thecompressor 42 in a room (step S64), and when impure gas is not detectedaround the compressor 42 (No at step S64), the machining is continued(step S70). After the machining process is completed, the detectingprocess is ended.

Meanwhile, when the impure gas is detected around the compressor 42 (Yesat step S64), the odor sensor 51 outputs the anomaly detection signal tothe control notification section 61. The control notification section 61notifies information showing that the compressor 42 and its vicinity areinspected to the anomaly display section 62 (step S65), and thisinformation is displayed on the anomaly display section 62. The operatormakes an inspection according to the information (step S26). Since theinspection of the compressor 42 and its vicinity by the operator is thesame as that in the first embodiment, the explanation thereof isomitted.

After the inspection and the replacement by the operator are ended, whenthe gas detector 50 does not detect anomaly of the atmosphere around thecompressor 42 (No at step S67), the machining is continued (step S70).After the machining process is completed, the detecting process isended. When the gas detector 50 detects anomaly of the atmosphere aroundthe compressor 42 (Yes at step S67), the odor sensor 51 outputs theanomaly detection signal to the control notification section 61. Thecontrol notification section 61 notifies information showing thatinspection of portions in the laser beam machining apparatus except forthe compressor 42 and its vicinity is necessary to the anomaly displaysection 62 (step S68), and the anomaly display section 62 displays thisinformation.

When the information is received, the operator judges whether themachining can be executed without affecting the machining quality in thestate where the output of the laser oscillator 11 is lowered, and thestate of the laser oscillator 11 is controlled by the controlnotification section based on the judged result (step S69). When thelaser beam machining can be carried out like the first embodiment, thecontrol notification section 61 adjusts the output of the laseroscillator 11 to the level where the machining quality is not affectedso that the machining is continued. When the continuation of themachining is difficult, the laser oscillator 11 is stopped. After thelaser oscillator 11 is stopped, the operator inspects the parts in thelaser beam machining, such as the transmission line parts including thepipes 31 a and 31 b and the bellows 33 of the optical duct 30 to be thetransmission line of the laser beam L except for the inspected andreplaced compressor 42, the machine including the frame 23, and thelaser oscillator 11. When anomaly is found, an anomalous part isreplaced, and the process is ended. The inspection of the transmissionline parts may be made when the machining is executed with the output ofthe laser beam being lowered.

According to the fourth embodiment, the odor sensor 51 is provided nearthe compressor 42 which supplies the purge gas, so as to be capable ofdetermining anomaly of the atmosphere around the compressor 42 in aroom. The operation of the laser oscillator 11 can be controlled basedon the information about the anomaly. The replacement timing of thefilter 43 provided to the inlet port of the compressor 42 can bedetermined by the anomaly detection signal output from the odor sensor51.

FIFTH EMBODIMENT

FIG. 12 is a schematic diagram of a laser beam machining apparatusaccording to a fifth embodiment of the present invention. FIG. 13 is toexplain how the odor sensor detects anomalous portions in the laser beammachining apparatus according to the fifth embodiment. FIG. 14 is aflowchart of a process to detect an anomaly in the laser beam machiningapparatus according to the fifth embodiment. Components which have sameor similar configuration or same or similar functions as those in FIG. 1are designated by the same reference numbers, and the explanationthereof is omitted.

As shown in FIG. 12, in the laser beam machining apparatus of the fifthembodiment, a first gas detector 50 a is provided near the purge gasexhaust port 36, a second gas detector 50 b is provided near the purgegas supply port 35, and a third gas detector 50 c is provided in avicinity of the inlet port of the compressor 42. Although not shown, thegas detectors may be provided in plurality. The other parts of theconfiguration are the same as those in FIG. 1. The position where thesecond gas detector 50 b is provided is desirably a portion on theoptical duct 30 opposed to the purge gas supply port 35 or its slightlylower stream side. The first and the second gas detectors 50 a and 50 bare arranged on the concave portion 70 provided on the optical duct 30as shown in FIG. 2 of the first embodiment.

FIG. 13 is a diagram of the causes which are conceivable from anomalydetected conditions of the first to the third gas detectors 50 a to 50c. In the drawing, similarly to FIG. 8, a circle represents thecondition where anomaly is not detected, and cross represents thecondition where anomaly is detected. When all the first to the third gasdetectors 50 a to 50 c are normal, since the impure gas does not flowinto the optical duct 30, the machining process can be continued. Whenthe first and the second gas detectors 50 a and 50 b are normal and thethird gas detector 50 c detects an anomaly, its first cause isconsidered to be impure gas in the atmosphere around the compressor 42.

When the first gas detector 50 a detects an anomaly and the second andthe third gas detectors 50 b and 50 c are normal, a determination can bemade that its first cause is anomaly of gas intruded from thetransmission line parts. When the first and the third gas detectors 50a, 50 c detect anomaly and the second gas detector 50 b is normal, adetermination can be made that its first cause is the atmosphere aroundthe compressor 42 and the transmission line parts.

When the first and the second gas detectors 50 a and 50 b detect anomalyand the third gas detector 50 c is normal, a determination can be madethat its first cause is anomaly between the compressor 42 and the purgegas supply port 35 on the optical duct 30, and its second cause is thetransmission line parts. When the first to the third gas detectors 50 ato 50 c detect anomaly, a determination can be made that its first causeis the atmosphere around the compressor 42, and its second cause is theanomaly between the compressor 42 and the purge gas supply port 35 onthe optical duct 30, and its third cause is the transmission line parts.

The first gas detector 50 a is provided near the purge gas exhaust port36 on the optical duct 30, the second gas detector 50 b is provided nearthe purge gas supply port 35 on the optical duct 30, and the third gasdetector 50 c is provided near the inlet port of the compressor 42.Consequently, a determination can be made whether the cause of theintrusion of the impure gas is anomaly due to the atmosphere around thecompressor 42, the compressor 42, or the transmission line parts.

A countermeasure against the anomaly due to the intrusion of the impuregas in the laser beam machining apparatus is taken from the upper streamside of the purge gas, namely, in order of the compressor 42 and itsvicinity, and the transmission line parts. A countermeasure methodagainst the causes of the anomaly in FIG. 13 can be roughly classifiedinto two, and when the normal time is added the method can be classifiedinto three. That is to say, the method can be classified into three: (A)the countermeasure when all the gas detectors 50 a to 50 c are normal;(B) the countermeasure when at least one of the second and the thirddetectors 50 b and 50 c detects anomaly (the cause is the compressor 42and its vicinity); and (C) the countermeasure when only the first gasdetector 50 a detects anomaly (the cause is the transmission lineparts).

The process of detecting anomaly in the laser beam machining apparatusis explained with reference to the flowchart of FIG. 14. The sameprocess as steps S61 to S63 explained in FIG. 11 of the fourthembodiment is executed, so that the machining is started by the laserbeam machining apparatus (step S81 to S83). That is to say, thecalibration of the odor sensor 51 is executed for predetermined time,and after the compressor 42 is booted and the optical duct 30 is filledwith gas (air), the machining is started. The calibration of the odorsensor 51 is executed in the procedure explained in FIG. 4 of the firstembodiment.

During the laser beam machining, the odor sensors 51 of the first to thethird gas detectors 50 a to 50 c continue to detect impure gas (stepS84). When all the gas detectors 50 a to 50 c detect no anomaly, (“allthe gas detectors are normal” at step S84), the machining is continued(step S93). The process ends after the machining process is completed.

When at least one of the second and the third gas detectors 50 b and 50c detects anomaly (“at least one of the second and the third gasdetectors detects anomaly” at step S84), the anomaly detection signal isoutput from any one of the second gas detector 50 b and the third gasdetector 50 c or both to the control notification section 61. Thecontrol notification section 61 notifies information that shows thecompressor 42 and its vicinity are inspected to the anomaly displaysection 62 (step S85), and the anomaly display section 62 displays thisinformation. The operator makes an inspection according to theinformation (step S86). Since the inspection of the compressor 42 andits vicinity by the operator are the same as those in the firstembodiment, the explanation thereof is omitted.

When the three gas detectors 50 a to 50 c do not detect anomaly due tothe impure gas (“all the gas detectors are normal” at step S87), themachining process is continued (step S93). The process ends after themachining process is completed.

Meanwhile, when only the first gas detector 50 a detects anomaly due tothe impure gas in the purge gas (“only the first gas detector detectsanomaly” at step S87), or when the only the first gas detector 50 adetects anomaly at step S84 (“only the first gas detector detectsanomaly” at step S84), the first gas detector 50 a outputs the anomalydetection signal to the control notification section 61. The controlnotification section 61 notifies information showing that thetransmission line parts are inspected to the anomaly display section 62(step S48), this information is displayed on the anomaly display section62. The operator makes an inspection according to the information (stepS89). The operator inspects the transmission line parts such as thepipes 31 a and 31 b, and the bellows 33 of the optical duct 30 to be thetransmission line of the laser beam L for burning and deterioration, andwhen anomaly is found, the operator replaces an anomalous part.

After the inspection and the replacement by the operator is ended, thegas detectors 50 a to 50 c detect impure gas in the optical duct 30(step S90). When the gas detectors 50 a to 50 c do not detect theanomaly due to the impure gas (No at step S90), the machining process iscontinued (step S93). The process ends after the machining process iscompleted.

When the gas detectors 50 a to 50 c detect the anomaly due to the impuregas in the purge gas (Yes at step S90), the gas detectors 50 a to 50 cwhich detect anomaly output the anomaly detection signal to the controlnotification section 61. The control notification section 61 notifiesinformation showing that the inspection of the entire laser beammachining apparatus is necessary to the anomaly display section 62 (stepS91), and this information is displayed on the anomaly display section62.

When the information is received, the operator judges whether themachining can be executed without affecting the machining quality in thestate where the output of the laser oscillator 11 is lowered. Thecontrol notification section 61 controls the state of the laseroscillator 11 based on the judged result (step S92). When the lasermachining can be executed like the first embodiment, the controlnotification section 61 adjusts the output of the laser oscillator 11 tothe level where the machining quality is not affected, so that themachining is continued. When the continuation of the machining isdifficult, the laser oscillator 11 is stopped. After the laseroscillator 11 is stopped, the operator inspects the parts in the laserbeam machining apparatus, such as the machine including the frame 23,and the laser oscillator 11 except for the inspected and replacedcompressor 42 and the optical duct 30. When anomaly is found, ananomalous part is replaced, and the process is ended.

According to the fifth embodiment, the odor sensor 51 is provided nearthe purge gas exhaust port 36, near the purge gas supply port 35, andnear the inlet port of the compressor 42. The intrusion of the impuregas can be, therefore, detected, and a determination can be made whetherits cause is the atmosphere around the compressor 42 in a room, thecompressor 42, or the transmission line. As a result, a location whichis the cause of the anomalous laser beam L can be checked uponeffectively. The anomaly due to the intrusion of the impure gas isoutput to the control notification section 61, so that the replacementtiming of the filter attached to the inlet port of the compressor 42,and the detected anomaly such as burning and deterioration of thetransmission line parts can be known easily. The laser oscillator 11 canbe controlled based on the anomaly detection signal from the controlnotification section 61.

The fifth embodiment explains that the odor sensor 51 provided near thepurge gas supply port 35, near the purge gas exhaust port 36, and nearthe inlet port of the compressor 42. Even if, however, the odor sensor51 is provided near the purge gas supply port 35 and near the inlet portof the compressor 42, or the odor sensor 51 is provided near the purgegas exhaust port 36 and near the inlet port of the compressor 42,namely, providing positions and a number of the odor sensors arechanged, the effect explained in the first to fourth embodiments can beobtained.

The first to fifth embodiments explain the configuration where themachining head 21 stands in vertical state, but the machining head 21may lie in a horizontal state, or the machining head 21 may rotate ortilt. The first to fifth embodiments explain that the machining head 21is movable only to a right-left direction, but the machining head 21 maybe movable to a vertical direction with respect to a sheet, may bemovable to both the directions, or may be movable three-dimensionally.The optical duct 30 from the laser oscillator 11 to the machining head21 which guides the laser beam L may have not an L shape in the first tofifth embodiments but an arbitrary shapes.

In the first to fifth embodiments, the valve 44, which selectivelyswitches between the compressor 42 and the nitrogen supply section 41 soas to guide sucked and compressed air from the compressor 42 or nitrogengas from the nitrogen supply section 41 to the optical duct 30, isprovided, and the filter 43 is attached to the inlet port of thecompressor 42. The valve 44 and the filter 43 are not, however,necessarily provided, or even if only one of them is provided, theeffect which is similar to that in the first to fifth embodiments can beobtained.

In the first to fifth embodiments, the purge gas supply port 35 isprovided near the laser outgoing port 12 of the laser oscillator 11 onthe optical duct 30, and the purge gas exhaust port 36 is provided nearthe attached position of the machining head 21 of the optical duct 30.On the contrary, the purge gas supply port 35 may be provided near theattached position of the machining head 21 of the optical duct 30, andthe purge gas exhaust port 36 may be provided near the laser outgoingport 12 of the laser oscillator 11 of the optical duct 30.

SIXTH EMBODIMENT

In the first to the third and the fifth embodiments, the gas detector 50is provided on the optical duct 30 as shown, for example, in FIG. 2. Ina sixth embodiment, however, the gas detector 50 is provided on theoptical duct 30 in a different form from FIG. 2.

FIG. 15 illustrates an example in which the gas detector is attached tothe optical duct. FIG. 16 is a flowchart of a process of calibrationexecuted using the gas detector.

As shown in FIG. 15, the gas detector 50 is provided on the concaveportion 70 which is formed in such a manner that a part of the side wallof the optical duct 30 is recessed from the inside to the outside of theoptical duct 30. The concave portion 70 has a surface parallel with theoptical axis in the optical duct 30, and is surrounded by the peripheralsurface 71 connected with the optical duct 30 and two side surfaces 74 aand 74 b which connect the outer peripheral surface of the optical duct30 with the peripheral surface 71 of the concave portion 70. The sidesurfaces 74 a and 74 b of the concave portion 70 has an angle that isapproximately vertical to the extended direction of the optical duct 30.

The odor sensor 51 of the gas detector 50 is fixed to an installationbase 81. The installation base 81 is connected with a driving mechanism82 such as a motor or an air cylinder, and is movable to an up-downdirection on the sheet between the concave portion 70 and a positionwhere the optical axis of the laser beam L in the optical duct 30 is notdisturbed. The installation stand 81 has a dimension which is theapproximately same as that of an opening of the concave portion 70. Atthe time of the calibration, the installation stand 81 is moved by thedriving mechanism 82 so that its surface opposite to the odor sensor 51forms a part of the inner wall of the optical duct 30 as drawn by asolid line in FIG. 15 and the odor sensor 51 is housed in the concaveportion 70. During the laser beam machining, the installation stand 81is moved by the driving mechanism 82 to a position in the optical duct30 where the optical path of the laser beam L is not disturbed as drawnby a dotted line in FIG. 15.

The sensor calibrator has the calibration gas supply section 53 whichsupplies calibration gas, a gas supply opening 56 which emits thecalibration gas into the concave portion 70, and the electromagneticvalve 55 which supplies the calibration gas into the optical duct 30 atthe time of executing the calibration and does not supply thecalibration gas into the optical duct 30 at the other time. Similarly toFIG. 2 of the first embodiment, the gas supply opening 56 is attached tothe side surface 74 b positioned on the upper stream side of the concaveportion 70. A gas exhaust port 57 which exhausts the calibration gas isprovided on the side surface 74 a of the concave portion 70 opposed tothe gas supply opening 56. The gas exhaust port 57 is opened only duringthe calibration, and is closed during the laser beam machining. The odorsensor 51 is connected with the control notification section 61 via thegas exhaust port 57.

The operation of the odor sensor is explained below with reference toFIG. 16. In order to execute the calibration, the odor sensor 51 ismoved by the driving mechanism 82 to a predetermined position in theconcave portion 70 (step S211). The process which is the same as stepsS201 to 205 in FIG. 4 is executed, so that the calibration of the odorsensor 51 is executed (steps S212 to S216). That is to say, theelectromagnetic valve 55 which is provided between the calibration gassupply section 53 and the gas supply opening 56 is opened, and thecalibration gas is emitted from the gas supply opening 56 to the odorsensor 51, so that the calibration is started. The calibration gas isemitted to the odor sensor 51 for predetermined time (normally a fewminutes), and when the calibration is ended, the odor sensor 51 outputsa signal that shows the completion of the calibration to the controlnotification section 61, so that the control notification section 61closes the electromagnetic valve 55.

The odor sensor 51 is moved by the driving mechanism 82 to thepredetermined position in the optical duct 30, and the calibrationprocess is ended (step S217).

The configuration of the gas detector 50 in the optical duct 30 can beapplied to the gas detector 50 in the first to third and fifthembodiments.

According to the sixth embodiment, at the time of the calibration of theodor sensor 51, the installation stand 81 is moved so as to cover theopening of the concave portion 70, and the calibration gas is allowed toflow into a space surrounded by the concave portion 70 and theinstallation stand 81. As a result, a quantity of the calibration gas tobe used at the time of the calibration can be suppressed.

SEVENTH EMBODIMENT

In the first through third embodiments and the fifth embodiment, the gasdetector 50 is provided on the optical duct 30, for example, as shown inFIG. 2. A seventh embodiment explains that the gas detector 50 isprovided in the optical duct 30 in a form different from FIG. 2.

FIG. 17 illustrates an example in which the gas detector is mounted tothe optical duct, and FIG. 18 is a flowchart of a process of calibrationexecuted using the gas detector. The components which are the same asthose in FIG. 2 are designated by the same reference numbers, and theexplanation thereof is omitted.

As shown in FIG. 17, gate valves 91 are provided on the optical duct 30on the upper stream side and the lower stream side of the concaveportion 70 so that the gas detector 50 of the seventh embodiment forms aclosed space in the optical duct 30 provided with the concave portion 70in FIG. 2 of the first embodiment.

When the odor sensor 51 is calibrated, the two gate valves 91 are closedso that the space in the optical duct 30 where the concave portion 70 isprovided is a closed space, and the calibration gas is supplied from thecalibration gas supply section 53 into the space. After the calibrationis ended, the gate valves 91 are opened, and the laser beam machining isexecuted.

The operation of the odor sensor 51 is explained below with reference toFIG. 18. Two gate valves 91 are closed, so that the space in the opticalduct 30 where the concave portion 70 is provided is a closed space (stepS221). The process which is the same as steps S201 to S206 in FIG. 4 isexecuted, so that the odor sensor 51 is calibrated (step S212 to S216).That is to say, the electromagnetic valve 55 provided between thecalibration gas supply section 53 and the nozzle 54 is opened, and thecalibration gas is emitted from the nozzle 54 onto the odor sensor 51 sothat the calibration is started. When the calibration gas is emittedonto the odor sensor 51 for predetermined time (normally, a few minutes)and the calibration is ended, the odor sensor 51 outputs a calibrationcompletion signal to the control notification section 61, and thecontrol notification section 61 closes the electromagnetic valve 55.

The gate valves 91 provided in the optical duct 30 are opened, and thecalibration process is ended (step S217).

The configuration of the gas detector 50 in the optical duct 30 can beapplied to the gas detector 50 of the first to third and fifthembodiments.

According to the seventh embodiment, the gate valves 91, which form theclosed space in the optical duct 30 provided with the concave portion70, are provided, and the gate valves 91 are closed at the time of thecalibration so that the calibration gas is sealed in the space in theoptical duct 30 including the concave portion 70. A use quantity of thecalibration gas can be suppressed in comparison with the configurationof the gas detector 50 in the first to third and fifth embodiments.

According to the present invention, the odor sensor is provided in theoptical duct of the laser beam machining apparatus or at the inlet portof the compressor or the like, so as to be capable of detecting anomalyof the entire purge gas including the optical duct. As a result, theintrusion of the impure gas can be specified as a cause of the anomalouslaser beam. The odor sensor outputs the anomaly detection signal to thecontrol notification section, and a determination is made which odorsensor outputs the anomaly detection signal, or as to how many times theanomaly detection signal is notified, thereby checking upon its causeeffectively. Defective machining during the machining by the laser beammachining apparatus can be, therefore, reduced, and the cause of thedefective machining can be found easily.

INDUSTRIAL APPLICABILITY

The present invention is suitable to the laser beam machining apparatuswhich executes the machining process such as welding and cutting on aworkpiece to be machined using the laser beam.

1. A laser beam machining apparatus, comprising: a laser oscillatorwhich oscillates a laser beam, the laser oscillator having a laser beamoutgoing port to output the laser beam; a machining head which machinesa workpiece with the laser beam; an optical duct with an optical systemto guide the laser beam from the laser beam outgoing port to themachining head; a purge gas supply port that opens into the optical ductand situated near any one of the laser beam outgoing port and themachining head, wherein a purge gas supply unit supplies purge gas intothe optical duct from the purge gas supply port; a purge gas exhaustport that opens into the optical duct and situated near any one of thelaser beam outgoing port and the machining head, wherein the purge gasin the optical duct is output from the purge gas exhaust port; and anodor sensor that detects undesired gas in a portion of the optical ductfrom the laser beam outgoing port to the machining head, wherein theundesired gas is a gas that makes the laser beam anomalous.
 2. The laserbeam machining apparatus according to claim 1, further comprising acontrol notification unit that, upon the odor sensor detecting theundesired gas, identifies a cause of the undesired gas entering theoptical duct and notifies the cause.
 3. The laser beam machiningapparatus according to claim 2, wherein the control notification unitincludes a counter that counts number of times the odor sensor detectsthe undesired gas from the time the laser beam machining apparatus isbooted, and if the count of the counter indicates that the odor sensorhas detected the undesired gas for a first time, the controlnotification identifies a faulty in the purge gas supply unit andperipheral atmosphere of the purge gas supply unit as the cause.
 4. Thelaser beam machining apparatus according to claim 2, wherein the controlnotification on unit includes a counter that counts number of times theodor sensor detects the undesired gas from the time the laser beammachining apparatus is booted, and if the count of the counter indicatesthat the odor sensor has detected the undesired gas for a second time,the control notification unit identifies a fault in the optical duct asthe cause.
 5. The laser beam machining apparatus according to claim 2,wherein the control notification unit includes a counter that countsnumber of times the odor sensor detects the undesired gas from the timethe laser beam machining apparatus is booted, and if the count of thecounter indicates that the odor sensor has detected the undesired gasfor third or more times, the control notification unit identifies afault in the entire laser beam machining apparatus as the cause andcontrols an operating state of the laser oscillator
 6. The laser beammachining apparatus according to claim 1, wherein the odor sensor issituated adjacent to the purge gas exhaust port.
 7. The laser beammachining apparatus according to claim 6, further comprising a controlnotification unit that, upon the odor sensor detecting the undesiredgas, identifies a cause of the undesired gas entering the optical ductand performs any one of notifying the cause and notifying the cause andcontrolling an operating state of the laser oscillator based on numberof times the odor sensor detects the undesired gas from the time thelaser beam machining apparatus is booted. 8-23. Cancelled
 24. The laserbeam machining apparatus according to claim 1, wherein the odor sensoris situated adjacent to the purge gas supply port.
 25. The laser beammachining apparatus according to claim 24, further comprising a controlnotification unit that, upon the odor sensor detecting the undesiredgas, identifies a cause of the undesired gas entering the optical ductand performs any one of notifying the cause and notifying the cause andcontrolling an operating state of the laser oscillator based on numberof times the odor sensor detects the undesired gas from the time thelaser beam machining apparatus is booted.
 26. The laser beam machiningapparatus according to claim 1, wherein the odor sensor includes a firstodor sensor situated adjacent to the purge gas exhaust port, and asecond odor sensor situated adjacent to the purge gas supply port. 27.The laser beam machining apparatus according to claim 26, furthercomprising a control notification unit that, upon any one of the firstodor sensor and the second odor sensor detecting the undesired gas,identifies a cause of the undesired gas entering the optical duct andperforms any one of notifying the cause and notifying the cause andcontrolling an operating state of the laser oscillator based on numberof times the first odor sensor and the second odor sensor detect theundesired gas from the time the laser beam machining apparatus isbooted, and based on which one of the first odor sensor and the secondodor sensor has detected the undesired gas.
 28. The laser beam machiningapparatus according to claim 27, wherein the purge gas supply unit hasan inlet port to suck air, a filter to filter dust from the air andobtain dust-free air, and a compressor to compress the dust-free air andsupply the compressed dust-free air to the optical duct, and when thesecond odor sensor detects the undesired gas for a first time after thelaser beam machining apparatus is booted, the control notificationidentifies a faulty in the purge gas supply unit and peripheralatmosphere of the purge gas supply unit as the cause.
 29. The laser beammachining apparatus according to claim 28, further comprising: a secondpurge gas supply unit that is situated in a flow channel connecting thecompressor and the purge gas supply port via a valve which selectivelyswitches the purge gas between the purge gas supply unit and thecompressor, the control notification unit switches the valve so that,when daily one of the first odor sensor and the second odor sensordetects the undesired gas when the purge gas is supplied from thecompressor to the optical duct, the purge gas is supplied from thesecond purge gas supply unit to the optical duct.
 30. The laser beammachining apparatus according to claim 1, wherein the purge gas supplyunit has an inlet port to suck air, a filter to filter dust from the airand obtain dust-free air, and a compressor to compress the dust-free airand supply the compressed dust-free air to the optical duct, and Theodor sensor includes a first odor sensor situated adjacent to the purgegas exhaust port, a second odor sensor situated adjacent to the purgegas supply port, and a third odor sensor situated adjacent to the inletport of the purge gas supply unit.
 31. The laser beam machiningapparatus according to claim 30, further comprising a controlnotification unit that, upon any one of the first odor sensor, thesecond odor sensor, and the third odor sensor detecting the undesiredgas, identifies a cause of the undesired gas entering the optical ductand performs any one of notifying the cause and notifying the cause andcontrolling an operating state of the laser oscillator based on numberof times the first odor sensor, the second odor sensor, and the thirdodor sensor detect the undesired gas from the time the laser beammachining apparatus is booted, and based on which one of the first odorsensor, the second odor sensor, and the third odor sensor has detectedthe undesired gas.
 32. The laser beam machining apparatus according toclaim 1, wherein the optical duct includes a concave portion to fit theodor sensor.
 33. The laser beam machining apparatus according to claim32, further comprising a calibration gas supply unit gas supply unitsituated near the odor sensor, wherein the calibration gas supply unitejects calibration gas towards the odor sensor for calibrating the odorsensor.
 34. The laser beam machining apparatus according to claim 33,further comprising a driving unit which moves the odor sensorsufficiently inside the concave portion when the odor sensor is beingcalibrated, and moves the odor sensor inside the conducting arrangementuntil the odor sensor does not disturb the path of the laser beam in theconducting arrangement when the workpiece is to be machined with thelaser beam.
 35. The laser beam machining apparatus according to claim33, further comprising two gate valves in positions on the optical ductsandwiching the concave portion, wherein the gate valves are closed whenthe odor sensor is being calibrated.